Synthetic Access to Noncanonical Strigolactones: Syntheses of Carlactonic Acid and Methyl Carlactonoate

Strigolactones
are plant hormones regulating essential stages of
a plant’s development. Their low natural abundance combined
with a low chemical stability significantly hampered the detailed
investigation of their biological activity. Noncanonical strigolactones
lack the fused tricyclic ABC-ring system commonly present in canonical-type
strigolactones but feature an open-chain unit linking structurally
diverse A-ring moieties to the butenolide D-ring. We herein present
an efficient synthetic access to enantiomerically pure noncanonical
strigolactones by a Stille cross-coupling approach to forge the central
diene moiety and demonstrate this strategy by syntheses of natural
products methyl carlactonoate and carlactonic acid. Furthermore, a
synthetic access to deuterium-labeled analogues of these natural products
has been developed.